Question: $\dfrac{5}{2} - \dfrac{9}{10} = {?}$
Answer: $ = {\dfrac{5 \times 5}{2 \times 5}} - {\dfrac{9 \times 1}{10 \times 1}} $ $ = {\dfrac{25}{10}} - {\dfrac{9}{10}} $ $ = \dfrac{{25} - {9}}{10} $ $ = \dfrac{16}{10}$